The program continues to be directed toward identifying pathways in the nervous system through the use of radiochemicals. For that purpose, radioactive substances are concentrated and injected either hydrolically or electrophoretically into various nerve tissues. Thereafter the preparation is allowed to survive for a period of time which has been established experimentally as sufficient to allow transport of the label to the most remote portions of the pathway under study. Through the use of autoradiography the location of the radiochemical is then established in serial sections of the tissues. In some cases semi-quantitative data on the number and position of labelled nerve elements are established through the use of automated techniques. These last named procedures include the development of both hardware and software to support our methods of analysis. The results obtained so far indicate that several neural pathways can be so examined. Data on sizes, numbers and location in nerve tissue of the labelled elements have been obtained. BIBLIOGRAPHIC REFERENCE: Whitlock, D.G., "Computer analysis of some ascending spinal pathways visualized by autoradiography," Cajal Club Symposium, American Association of Anatomists, 1976.